2023-05-30 16:43:22

by Azeem Shaikh

Subject: [PATCH] clocksource: Replace all non-returning strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <[email protected]>
---
kernel/time/clocksource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 91836b727cef..88cbc1181b23 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -1480,7 +1480,7 @@ static int __init boot_override_clocksource(char* str)
{
mutex_lock(&clocksource_mutex);
if (str)
- strlcpy(override_name, str, sizeof(override_name));
+ strscpy(override_name, str, sizeof(override_name));
mutex_unlock(&clocksource_mutex);
return 1;
}

2023-05-30 18:26:36

by John Stultz

Subject: Re: [PATCH] clocksource: Replace all non-returning strlcpy with strscpy

On Tue, May 30, 2023 at 9:35 AM Azeem Shaikh <[email protected]> wrote:
>
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <[email protected]>
> ---
> kernel/time/clocksource.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
> index 91836b727cef..88cbc1181b23 100644
> --- a/kernel/time/clocksource.c
> +++ b/kernel/time/clocksource.c
> @@ -1480,7 +1480,7 @@ static int __init boot_override_clocksource(char* str)
> {
> mutex_lock(&clocksource_mutex);
> if (str)
> - strlcpy(override_name, str, sizeof(override_name));
> + strscpy(override_name, str, sizeof(override_name));
> mutex_unlock(&clocksource_mutex);
> return 1;
> }

Sounds reasonable to me.

Acked-by: John Stultz <[email protected]>

Thanks for submitting this!
-john

2023-05-30 23:49:03

by Kees Cook

Subject: Re: [PATCH] clocksource: Replace all non-returning strlcpy with strscpy

On Tue, 30 May 2023 16:35:46 +0000, Azeem Shaikh wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> No return values were used, so direct replacement is safe.
>
> [...]

Applied to for-next/hardening, thanks!

[1/1] clocksource: Replace all non-returning strlcpy with strscpy
https://git.kernel.org/kees/c/40932d192ec8

--
Kees Cook